Cationic poly(lactide-co-glycolide) nanoparticles as efficient in vivo gene transfection agents

Mannose-Modified Chitosan Poly(lactic-co-glycolic acid) Microspheres Act as a Mannose Receptor-Mediated Delivery System Enhancing the Immune Response

The mannose receptor (MAN-R)-targeted delivery system is commonly used to deliver antigens to macrophages or immature dendritic cells (DCs) to promote the efficiency of antigen presentation. To maximize the enhancement effects of chitosan (CS) and induce an efficient humoral and cellular immune response against an antigen, we encapsulated ovalbumin (OVA) in poly(lactic-co-glycolic acid) (PLGA) microspheres (MPs) and conjugated it with MAN-modified CS to obtain MAN-R-targeting nano-MPs (MAN-CS-OVA-PLGA-MPs). The physicochemical properties, drug loading rate, and immunomodulation activity of MAN-CS-OVA-PLGA-MPs were evaluated. In vitro, MAN-CS-OVA-PLGA-MPs (80 μg mL⁻¹) could enhance the proliferation of DCs and increase their phagocytic efficiency. In vivo, MAN-CS-OVA-PLGA-MPs significantly increased the ratio of CD3⁺CD4⁺/CD3⁺CD8⁺ T cells, increased CD80⁺, CD86⁺, and MHC II expression in DCs, and improved OVA-specific IgG, IgG1, IgG2a, and IgG2b antibodies. Moreover, MAN-CS-OVA-PLGA-MPs promoted cytokine (IFN-γ, IL-4, and IL-6) production in mice. Taken together, our results show that MAN-CS-OVA-PLGA-MPs may act by activating the T cells to initiate an immune response by promoting the maturation of dendritic cells and improving their antigen presentation efficiency. The current study provides a basis for the use of MAN-CS-OVA-PLGA-MPs as an antigen and adjuvant delivery system targeting the MAN-R on the surface of macrophages and dendritic cells.

PLGA-based nanomedicines manufacturing: Technologies overview and challenges in industrial scale-up

Nanomedicines based on poly(lactic-co-glycolic acid) (PLGA) carriers offer tremendous opportunities for biomedical research. Although several PLGA-based systems have already been approved by both the Food and Drug Administration (FDA) and the European Medicine Agency (EMA), and are widely used in the clinics for the treatment or diagnosis of diseases, no PLGA nanomedicine formulation is currently available on the global market. One of the most impeding barriers is the development of a manufacturing technique that allows for the transfer of nanomedicine production from the laboratory to an industrial scale with proper characterization and quality control methods. This review provides a comprehensive overview of the technologies currently available for the manufacturing and analysis of polymeric nanomedicines based on PLGA nanoparticles, the scale-up challenges that hinder their industrial applicability, and the issues associated with their successful translation into clinical practice.

Fate of Biodegradable Engineered Nanoparticles Used in Veterinary Medicine as Delivery Systems from a One Health Perspective

The field of veterinary medicine needs new solutions to address the current challenges of antibiotic resistance and the need for increased animal production. In response, a multitude of delivery systems have been developed in the last 20 years in the form of engineered nanoparticles (ENPs), a subclass of which are polymeric, biodegradable ENPs, that are biocompatible and biodegradable (pbENPs). These platforms have been developed to deliver cargo, such as antibiotics, vaccines, and hormones, and in general, have been shown to be beneficial in many regards, particularly when comparing the efficacy of the delivered drugs to that of the conventional drug applications. However, the fate of pbENPs developed for veterinary applications is poorly understood. pbENPs undergo biotransformation as they are transferred from one ecosystem to another, and these transformations greatly affect their impact on health and the environment. This review addresses nanoparticle fate and impact on animals, the environment, and humans from a One Health perspective.

A review on versatile applications of blends and composites of CNC with natural and synthetic polymers with mathematical modeling

Cellulose is world's most abundant, renewable and recyclable polysaccharide on earth. Cellulose is composed of both amorphous and crystalline regions. Cellulose nanocrystals (CNCs) are extracted from crystalline region of cellulose. The most attractive feature of CNC is that it can be used as nanofiller to reinforce several synthetic and natural polymers. In this article, a comprehensive overview of modification of several natural and synthetic polymers using CNCs as reinforcer in respective polymer matrix is given. The immense activities of CNCs are successfully utilized to enhance the mechanical properties and to broaden the field of application of respective polymer. All the technical scientific issues have been discussed highlighting the recent advancement in biomedical and packaging field.

Enhancing the Delivery of Chemotherapeutics: Role of Biodegradable Polymeric Nanoparticles

While pharmaceutical drugs have revolutionized human life, there are several features that limit their full potential. This review draws attention to some of the obstacles currently facing the use of chemotherapeutic drugs including low solubility, poor bioavailability and high drug dose. Overcoming these issues will further enhance the applicability and potential of current drugs. An emerging technology that is geared towards improving overall therapeutic efficiency resides in drug delivery systems including the use of polymeric nanoparticles which have found widespread use in cancer therapeutics. These polymeric nanoparticles can provide targeted drug delivery, increase the circulation time in the body, reduce the therapeutic indices with minimal side-effects, and accumulate in cells without activating the mononuclear phagocyte system (MPS). Given the inroads made in the field of nanodelivery systems for pharmaceutical applications, it is of interest to review and emphasize the importance of Polymeric nanocarrier system for drug delivery in chemotherapy.

Gelation and thermal characteristics of microwave extracted fish gelatin-natural gum composite gels

In this study, the gelation and thermal characteristics of microwave extracted fish scale gelatin blended with natural gums such as gum arabic (AG), xanthan gum (XG), guar gum (GG), and tragacanth gum (TG) was evaluated. The nature of interaction and behavior of gelatin in presence of various gums was confirmed by particle size analysis, viscosity profile, FT-IR analysis and turbidity measurements. DSC data revealed that addition of AG, TG and GG remarkably improved the thermal stability of fish gelatin gel. The composite gels of TG, AG, and XG exhibited higher hardness and bloom strength values as compared to pure fish gelatin implying its textural synergy. Based on qualitative descriptive analysis, TG was found to be superior in improving the stability of fish gelatin gel, closely followed by AG. The results suggest that addition of these gums can reduce syneresis and retard melting of gelatin gels at ambient temperature, which are otherwise soft and thermally unstable.

Influence of different stabilizers on the encapsulation of desmopressin acetate into PLGA nanoparticles

To address targeting and bioavailability issues of peptidic drugs like desmopressin, the encapsulation into nanoparticles (NP) has become standard in pharmaceutics. This study investigated the encapsulation of desmopressin into PLGA NP by the use of pharmaceutically common stabilizers as a precursor to future, optional targeting and bioavailability experiments. Polymer dry weights were measured by freeze drying and thermo gravimetric analysis (TGA). Particle sizes (ranging between 105 and 130nm, PDI<0.1) and zeta potentials (-35 to -45mV) were analyzed with Dynamic Light Scattering (DLS) and Laser-Doppler-Anemometry (LDA) respectively. Highest loading efficiencies, quantified by RP-HPLC, were achieved with Pluronic F-68 as stabilizer of the inner aqueous phase (1.16±0.07μg desmopressin/mg PLGA) and were significantly higher than coating approaches and approaches without stabilizer (0.74±0.01μg/mg). Optimized nanoformulations are thus in competition with the concentration of commercial non-nanoparticulate desmopressin products. Stability of desmopressin after the process was evaluated by HPLC peak purity analysis (diode array detector) and by mass spectrometry. Desmopressin was shown to remain intact during the whole process; however, despite these very good results the encapsulation efficiency turned out to be a bottle neck and makes the system a challenge for potential applications.

Improved mucoadhesion and cell uptake of chitosan and chitosan oligosaccharide surface-modified polymer nanoparticles for mucosal delivery of proteins

The main aim of the present study was to compare mucoadhesion and cellular uptake efficiency of chitosan (CS) and chitosan oligosaccharide (COS) surface-modified polymer nanoparticles (NPs) for mucosal delivery of proteins. We have developed poly (D, L-lactide-co-glycolide) (PLGA) NPs, surface-modified COS-PLGA NPs and CS-PLGA NPs, by using double emulsion solvent evaporation method, for encapsulating bovine serum albumin (BSA) as a model protein. Surface modification of NPs was confirmed using physicochemical characterization methods such as particle size and zeta potential, SEM, TEM and FTIR analysis. Both surface-modified PLGA NPs displayed a slow release of protein compared to PLGA NPs. Furthermore, we have explored the mucoadhesive property of COS as a material for modifying the surface of polymeric NPs. During in vitro mucoadhesion test, positively charged COS-PLGA NPs and CS-PLGA NPs exhibited enhanced mucoadhesion, compared to negatively charged PLGA NPs. This interaction was anticipated to improve the cell interaction and uptake of NPs, which is an important requirement for mucosal delivery of proteins. All nanoformulations were found to be safe for cellular delivery when evaluated in A549 cells. Moreover, intracellular uptake behaviour of FITC-BSA loaded NPs was extensively investigated by confocal laser scanning microscopy and flow cytometry. As we hypothesized, positively charged COS-PLGA NPs and CS-PLGA NPs displayed enhanced intracellular uptake compared to negatively charged PLGA NPs. Our results demonstrated that CS- and COS-modified polymer NPs could be promising carriers for proteins, drugs and nucleic acids via nasal, oral, buccal, ocular and vaginal mucosal routes.

Current Uses of Poly(lactic-co-glycolic acid) in the Dental Field: A Comprehensive Review

Poly(lactic-co-glycolic acid) or PLGA is a biodegradable polymer used in a wide range of medical applications. Specifically PLGA materials are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA membranes have been studied with promising results, either alone or combined with other materials in bone healing procedures. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence that the development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in the dental field.

Biosafe nanoscale pharmaceutical adjuvant materials

Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes.

Reversal of multidrug resistance in vitro by co-delivery of MDR1 targeting siRNA and doxorubicin using a novel cationic poly(lactide-co-glycolide) nanoformulation

Over expression of drug efflux transporters such as P-glycoprotein (P-gp) cumulatively leading to multidrug resistance (MDR) embodies a major hindrance for successful cancer therapy. A paradigm nanomedicinal approach involving an anticancer drug and modulators of drug resistance within one multifunctional nanocarrier-based delivery system represent an ideal modality for the treatment of MDR. In this regards, we have developed a cationic polymeric nanoparticulate system loaded with MDR1-siRNA and doxorubicin. Results indicated augmented synergistic effect of combinational nanoformulation in overcoming MDR in MCF-7/ADR cells. Therefore, the above regime could be a promising co-delivery system for effective therapy of drug resistant breast cancer.

Microinjection free delivery of miRNA inhibitor into zygotes

The development of gene delivery systems into embryos is challenging due to technical difficulties, delivery efficiency and toxicity. Here, we developed an organic compound (VisuFect)-mediated gene delivery system for zygotes. The VisuFect, which is hydrophilic and Cy5.5-labeled, was conjugated with poly(A) oligo (VFA). The VFA into CHO cells showed clathrin-mediated internalization and no toxicity. The VFA successfully penetrated through the zona pellucida of fertilized eggs of various species including pigs, zebrafish, drosophilas and mice. The experiment with VisuFect-mediated delivery of the miR34c inhibitor showed similar results with direct microinjection of the miR34c inhibitor by suppressing the development of zygotes up to the blastocyst stage. Noticeable features of the VisuFect will provide great benefits for further studies on gene function in sperms and embryos.

Current progress in gene delivery technology based on chemical methods and nano-carriers

Gene transfer methods are promising in the field of gene therapy. Current methods for gene transfer include three major groups: viral, physical and chemical methods. This review mainly summarizes development of several types of chemical methods for gene transfer in vitro and in vivo by means of nano-carriers like; calcium phosphates, lipids, and cationic polymers including chitosan, polyethylenimine, polyamidoamine dendrimers, and poly(lactide-co-glycolide). This review also briefly introduces applications of these chemical methods for gene delivery.

Photodynamic effects of methylene blue-loaded polymeric nanoparticles on dental plaque bacteria

BACKGROUND AND OBJECTIVES

Photodynamic therapy (PDT) is increasingly being explored for treatment of oral infections. Here, we investigate the effect of PDT on human dental plaque bacteria in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles with a positive or negative charge and red light at 665 nm.

STUDY DESIGN/MATERIALS AND METHODS

Dental plaque samples were obtained from 14 patients with chronic periodontitis. Suspensions of plaque microorganisms from seven patients were sensitized with anionic, cationic PLGA nanoparticles (50 µg/ml equivalent to MB) or free MB (50 µg/ml) for 20 min followed by exposure to red light for 5 min with a power density of 100 mW/cm2 . Polymicrobial oral biofilms, which were developed on blood agar in 96-well plates from dental plaque inocula obtained from seven patients, were also exposed to PDT as above. Following the treatment, survival fractions were calculated by counting the number of colony-forming units.

RESULTS

The cationic MB-loaded nanoparticles exhibited greater bacterial phototoxicity in both planktonic and biofilm phase compared to anionic MB-loaded nanoparticles and free MB, but results were not significantly different (P > 0.05).

CONCLUSION

Cationic MB-loaded PLGA nanoparticles have the potential to be used as carriers of MB for PDT systems.

Triggered rapid degradation of nanoparticles for gene delivery

Effective gene delivery tools offer the possibility of addressing multiple diseases; current strategies rely on viruses or polyplexes. Encapsulation of DNA within nanoparticles is an attractive alternative method for gene delivery. We investigated the use of our recently developed Logic Gate Nanoparticle for gene delivery. The nanoparticles, composed of a dual pH response random copolymer (poly-β-aminoester ketal-2), can undergo a two-step “in series” response to endosomal pH. The first sep is a hydrophobic-hydrophilic switch, which is followed immediately by rapid degradation. Rapid fragmentation is known to increase cytoplasmic delivery from nanoparticles. Therefore, we hypothesized that our Logic Gate Nanoparticles would enable increased gene delivery and expression relative to nanoparticles that degrade more slowly such as PLGA-based nanoparticles. Passive nanoparticle entry into cells was demonstrated by delivering Cy5-labeled pDNA encoding EGFP into HCT116, a colon carcinoma cell line. Flow cytometry analysis showed that cells are positive for Cy5-DNA-nanoparticles and produced EGFP expression superior to PLGA nanoparticles. Inhibition of V-ATPases using bafilomycin A1 demonstrates that expression of EGFP is dependent on low endosomal pH. The advanced Logic Gate Nanoparticles offer new therapeutic possibilities in gene delivery and other applications where rapid release is important.

Pulmonary delivery and tissue distribution of aerosolized antisense 2'-O-Methyl RNA containing nanoplexes in the isolated perfused and ventilated rat lung

Pulmonary delivery of drugs, particularly in the treatment of lung cancer, is an attractive strategy for future targeted therapy. In this context, inhalation of nanoplexes might offer a new mode for drug delivery in gene therapy. However, limited data are currently available demonstrating pulmonary delivery, cellular uptake as well as local tolerability in lung tissue. The aim of this study was to elucidate the pulmonary delivery, tissue distribution and local tolerability of aerosolized chitosan-coated poly(lactide-co-glycolide) based nanoplexes containing antisense 2'-O-Methyl RNA (OMR). Therefore, an aerosol of OMR-nanoplexes or OMR alone was administered intra-tracheally using the model of the isolated perfused and ventilated rat lung. Localization of OMR in rat lung tissue was examined by immunohistochemistry. Administration of the OMR-nanoplex formulation resulted in significantly higher cellular OMR uptake of the respiratory epithelium in contrast to the administration of OMR alone, indicating that drug administration via aerosolized nanoplexes is able to target lung tissue. No prominent changes in lung physiology parameters were observed following inhalation, suggesting good local tolerability of OMR-nanoplex formulation.

Pulmonary gene delivery using polymeric nonviral vectors

Pulmonary delivery provides an easy and well tolerated means of access for the administration of biomacromolecules to the pulmonary epithelium and could therefore be an attractive approach for local and systemic therapies. A growing number of reports, which are summarized in this review, mirror the viability of pulmonary gene delivery. Special attention has been paid to the biological barriers in the lung that must be overcome for successful delivery, and which can be divided into anatomic, physical, immunologic, and metabolic barriers. In light of these barriers, successful nonviral polymer-based formulations of therapeutic genes are presented depending on the chemical nature of the polymer. In addition to polyethyleneimine-based nonviral vectors, which have been most intensively studied for pulmonary gene delivery in the past, other polymeric, dendritic, and targeted materials are also described here, including novel and biodegradable polymers. As new materials need in vitro or ex vivo testing before in vivo application, sophisticated models for all three approaches have been illustrated. Although pulmonary siRNA delivery enjoys popularity in clinical trials, pulmonary gene delivery has so far not been translated into clinical applications. With this review, potential hurdles are demonstrated, but novel approaches that may lead to optimized systems are described as well.

Anti-inflammatory and antiangiogenic effects of nanoparticle-mediated delivery of a natural angiogenic inhibitor

PURPOSE

The purpose of this study was to evaluate the inhibitory effects of the nanoparticle-mediated delivery of plasminogen kringle 5 (K5) on choroidal neovascularization (CNV) and retinal inflammation.

METHODS

CNV was induced by laser in adult rats. Nanoparticles with an expression plasmid of K5 (K5-NP) were injected into the vitreous. K5 expression was detected by immunohistochemistry. The CNV area was measured after fluorescein angiography. Retinal vascular permeability was quantified with Evans blue as a tracer. Expression of vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, and intercellular adhesion molecule (ICAM)-1 was measured by Western blot analysis or ELISA and real-time RT-PCR.

RESULTS

Intense K5 expression was detected in the retina 2 weeks after the injection of K5-NP. Areas of CNV were significantly decreased in the K5-NP treatment group compared with that in the control-NP group. The K5-NP injection also significantly reduced vascular permeability. The expression of VEGF was downregulated by K5-NP at both the protein and mRNA levels. Moreover, K5-NP also inhibited expression of TNF-α and ICAM-1. Similarly, K5-NP decreased retinal levels of total β-catenin. In cultured cells, K5-NP suppressed hypoxia-induced secretion of MCP-1 and TNF-α.

CONCLUSIONS

K5 has a novel anti-inflammatory activity. K5-NP mediates a sustained inhibitory effect on CNV and thus has therapeutic potential for age-related macular degeneration.

Biodegradable polymeric nanoparticles based drug delivery systems

Biodegradable nanoparticles have been used frequently as drug delivery vehicles due to its grand bioavailability, better encapsulation, control release and less toxic properties. Various nanoparticulate systems, general synthesis and encapsulation process, control release and improvement of therapeutic value of nanoencapsulated drugs are covered in this review. We have highlighted the impact of nanoencapsulation of various disease related drugs on biodegradable nanoparticles such as PLGA, PLA, chitosan, gelatin, polycaprolactone and poly-alkyl-cyanoacrylates.

Functionalized magnetic nanoparticles as an in vivo delivery system

We developed extremely small functionalized magnetic nanoparticles (MNPs) for use as an in vivo delivery system for pharmaceuticals and biomolecules. We functionalized the MNPs (d = 3 nm) by silanization of amino groups on the particles with (3-aminopropyl)triethoxysilane for subsequent cross-linking with pharmaceuticals and biomolecules. The MNPs were successfully introduced into living cells without any further modification, such as the use of cationic residues, to enhance endocytic internalization. The particles could be incorporated into the subcutaneous tissue of a mouse's ear through the skin of the ear and could be localized by application of an external magnetic field.We also developed a cell-specific delivery system that makes use of MNPs (d = 3 nm) conjugated with folic acid and a coumarin fluorophore for recognition by folate receptors on the cell surface. The modified MNPs were internalized by human pharyngeal cancer cells (KB cells) after an incubation time that was short compared with the time required for internalization of MNPs without folic acid. Cellular recognition of MNPs may lead to the development of other cell-specific delivery systems.These functionalized MNPs are expected to be useful as a new drug delivery tool.

Nanoparticle mediated delivery of 2'-O-methyl-RNA leads to efficient telomerase inhibition and telomere shortening in human lung cancer cells

A promising approach for treatment of non-small cell lung cancer (NSCLC) is based on the inhibition of telomerase in cancer cells. The antisense oligonucleotide 2'-O-methyl-RNA binding to the RNA component of telomerase acts as a selective telomerase inhibitor. We developed chitosan-coated polylactide-coglycolide (PLGA) nanoparticles to mediate efficient delivery of 2'-O-methyl-RNA into human lung cancer cells. Cellular uptake of the inhibitor mediated by chitosan-coated PLGA nanoparticles was greatly enhanced compared to the uptake of antisense oligonucleotide alone as shown by flow cytometry analysis. Confocal laser scanning microscopy clearly demonstrated internalization of 2'-O-methyl-RNA. 2'-O-methyl-RNA-nanoparticle complexes exhibited nearly no acute cytotoxicity in human lung cancer cells and did not influence the viability of primary tumor lung fibroblasts. Human NSCLC A549 cells treated with 2'-O-methyl-RNA-nanoparticle complexes showed 87% viability compared to untreated control cells. 2'-O-methyl-RNA delivered by nanoparticle complexes inhibited telomerase activity in a sequence-specific manner. During long-term treatment (15 weeks) telomerase activity was continuously reduced by approximately 80%. Furthermore, nanoparticle mediated delivery of 2'-O-methyl-RNA resulted in significant telomere shortening from 5.9kb to 4kb (p=0.008) in A549 cells. In summary, our data demonstrate that nanoparticle mediated delivery of 2'-O-methyl-RNA induces effective telomerase inhibition and telomere shortening in human lung cancer cells and therefore represents a novel and promising strategy for the treatment of lung cancer.

Nanoparticle-mediated expression of an angiogenic inhibitor ameliorates ischemia-induced retinal neovascularization and diabetes-induced retinal vascular leakage

OBJECTIVE

The aim of the study is to evaluate the effect of nanoparticle-mediated gene delivery of angiogenic inhibitors on retinal inflammation, vascular leakage, and neovascularization in diabetic retinopathy.

RESEARCH DESIGN AND METHODS

An expression plasmid of plasminogen kringle 5 (K5), a natural angiogenic inhibitor, was encapsulated with poly(lactide-coglycolide) to form K5 nanoparticles (K5-NP). Expression of K5 was determined by Western blot analysis and immunohistochemistry, and retinal vascular leakage was measured by permeability assay. Retinal neovascularization was evaluated using fluorescein-angiography and counting preretinal vascular cells in rats with oxygen-induced retinopathy. Effects of K5-NP on retinal inflammation were evaluated in streptozotocin-induced diabetic rats by leukostasis assay and Western blot analysis of intracellular adhesion molecule and vascular endothelial growth factor. Possible toxicities of K5-NP were evaluated using histology examination, retinal thickness measurement, and electroretinogram recording.

RESULTS

K5-NP mediated efficient expression of K5 and specifically inhibited growth of endothelial cells. An intravitreal injection of K5-NP resulted in high-level expression of K5 in the inner retina of rats during the 4 weeks they were analyzed. Injection of K5-NP significantly reduced retinal vascular leakage and attenuated retinal neovascularization, when compared with the contralateral eyes injected with Control-NP in oxygen-induced retinopathy rats. K5-NP attenuated vascular endothelial growth factor and intracellular adhesion molecule-1 overexpression and reduced leukostasis and vascular leakage for at least 4 weeks after a single injection in the retina of streptozotocin-induced diabetic rats. No toxicities of K5-NP were detected to retinal structure and function.

CONCLUSIONS

K5-NP mediates efficient and sustained K5 expression in the retina and has therapeutic potential for diabetic retinopathy.

Understanding the adsorption mechanism of chitosan onto poly(lactide-co-glycolide) particles

Polyelectrolyte-coated nanoparticles or microparticles interact with bioactive molecules (peptides, proteins or nucleic acids) and have been proposed as delivery systems for these molecules. However, the mechanism of adsorption of polyelectrolyte onto particles remains unsolved. In this study, cationic poly(lactide-co-glycolide) (PLGA) nanoparticles were fabricated by adsorption of various concentrations of a biodegradable polysaccharide, chitosan (0-2.4g/L), using oil-in-water emulsion and solvent evaporation techniques. The particle diameter, zeta-potential, and chitosan adsorption of chitosan-coated PLGA nanoparticles confirmed the increase of polyelectrolyte adsorption. Five adsorption isotherm models (Langmuir, Freundlich, Halsey, Henderson, and Smith) were applied to the experimental data in order to better understand the mechanism of adsorption. Both particle diameter and chitosan adsorption increased with chitosan concentration during adsorption. A good correlation was obtained between PLGA-chitosan nanoparticle size and adsorbed chitosan on the surface, suggesting that the increased particle size was primarily due to the increased chitosan adsorption. The zeta-potential of chitosan-coated PLGA nanoparticles was positive and increased with chitosan adsorbed until a maximum value (+55mV) was reached at approximately 0.4-0.6g/L; PLGA nanoparticles had a negative zeta-potential (-20mV) prior to chitosan adsorption. Chitosan adsorption on PLGA nanoparticles followed a multilayer adsorption behavior, although the Langmuir monolayer equation held at low concentrations of chitosan. The underlying reasons for adsorption of chitosan on PLGA nanoparticles were thought to be the cationic nature of chitosan, high surface energy and microporous non-uniform surface of PLGA nanoparticles.

Chitosan-coated PLGA nanoparticles for DNA/RNA delivery: effect of the formulation parameters on complexation and transfection of antisense oligonucleotides

Cationically modified poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles have recently been introduced as novel carriers for DNA/RNA delivery. The colloidal characteristics of the nanoparticles--particle size and surface charge--are considered the most significant determinants in the cellular uptake and trafficking of the nanoparticles. Therefore, our aim was to introduce chitosan-coated PLGA nanoparticles, whose size and charge are tunable to adapt for a specific task. The results showed that biodegradable nanoparticles as small as 130 nm and adjustable surface charge can be tailored controlling the process parameters. As a proof of concept, the overall potential of these particulate carriers to bind the antisense oligonucleotides, 2'-O-methyl-RNA, and improve their cellular uptake was demonstrated. The study proved the efficacy of chitosan-coated PLGA nanoparticles as a flexible and efficient delivery system for antisense oligonucleotides to lung cancer cells.

Preparation, characterization and transfection efficiency of cationic PEGylated PLA nanoparticles as gene delivery systems

The cationic polylactic acid (PLA) nanoparticle has emerged as a promising non-viral vector for gene delivery because of its biocompatibility and biodegradability. However, they are not capable of prolonging gene transfer and high transfection efficiency. In order to achieve prolonged delivery of cationic PLA/DNA complexes and higher transfection efficiency, in this study, we used copolymer methoxypolyethyleneglycol-PLA (MePEG-PLA), PLA and chitosan (CS) to prepare MePEG-PLA-CS NPs and PLA-CS NPs by a diafiltration method and prepared NPs/DNA complexes through the complex coacervation of nanoparticles with the pDNA. The object of our work is to evaluate the characterization and transfection efficiency of MePEG-PLA-CS versus PLA-CS NPs. The MePEG-PLA-CS NPs have a zeta potential of 15.7 mV at pH 7.4 and size under 100 nm, while the zeta potential of PLA-CS NPs was only 4.5 mV at pH 7.4. Electrophoretic analysis suggested that both MePEG-PLA-CS NPs and PLA-CS NPs with positive charges could protect the DNA from nuclease degradation and cell viability assay showed MePEG-PLA-CS NPs exhibit a low cytotoxicity to normal human liver cells. The potential of PLA-CS NPs and MePEG-PLA-CS NPs as a non-viral gene delivery vector to transfer exogenous gene in vitro and in vivo were examined. The pDNA being carried by MePEG-PLA-CS NPs, PLA-CS NPs and lipofectamine could enter and express in COS7 cells. However, the transfection efficiency of MePEG-PLA-CS/DNA complexes was better than PLA-CS/DNA and lipofectamine/DNA complexes by inversion fluorescence microscope and flow cytometry. It was distinctively to find that the transfection activity of PEGylation of complexes was improved. The nanoparticles were also tested for their ability to transport across the gastrointestinal mucosa in vivo in mice. In vivo experiments showed obviously that MePEG-PLA-CS/DNA complexes mediated higher gene expression in stomach and intestine of BALB/C mice compared to PLA-CS/DNA and lipofectamine/DNA complexes. These results suggested that MePEG-PLA-CS NPs have favorable properties for non-viral gene delivery.

Nanostructured materials for applications in drug delivery and tissue engineering

Research in the areas of drug delivery and tissue engineering has witnessed tremendous progress in recent years due to their unlimited potential to improve human health. Meanwhile, the development of nanotechnology provides opportunities to characterize, manipulate and organize matter systematically at the nanometer scale. Biomaterials with nano-scale organizations have been used as controlled release reservoirs for drug delivery and artificial matrices for tissue engineering. Drug-delivery systems can be synthesized with controlled composition, shape, size and morphology. Their surface properties can be manipulated to increase solubility, immunocompatibility and cellular uptake. The limitations of current drug delivery systems include suboptimal bioavailability, limited effective targeting and potential cytotoxicity. Promising and versatile nano-scale drug-delivery systems include nanoparticles, nanocapsules, nanotubes, nanogels and dendrimers. They can be used to deliver both small-molecule drugs and various classes of biomacromolecules, such as peptides, proteins, plasmid DNA and synthetic oligodeoxynucleotides. Whereas traditional tissue-engineering scaffolds were based on hydrolytically degradable macroporous materials, current approaches emphasize the control over cell behaviors and tissue formation by nano-scale topography that closely mimics the natural extracellular matrix (ECM). The understanding that the natural ECM is a multifunctional nanocomposite motivated researchers to develop nanofibrous scaffolds through electrospinning or self-assembly. Nanocomposites containing nanocrystals have been shown to elicit active bone growth. Drug delivery and tissue engineering are closely related fields. In fact, tissue engineering can be viewed as a special case of drug delivery where the goal is to accomplish controlled delivery of mammalian cells. Controlled release of therapeutic factors in turn will enhance the efficacy of tissue engineering. From a materials point of view, both the drug-delivery vehicles and tissue-engineering scaffolds need to be biocompatible and biodegradable. The biological functions of encapsulated drugs and cells can be dramatically enhanced by designing biomaterials with controlled organizations at the nanometer scale. This review summarizes the most recent development in utilizing nanostructured materials for applications in drug delivery and tissue engineering.

Nanoparticles: health effects--pros and cons

With the advent of nanotechnology, the prospects for using engineered nanomaterials with diameters of < 100 nm in industrial applications, medical imaging, disease diagnoses, drug delivery, cancer treatment, gene therapy, and other areas have progressed rapidly. The potential for nanoparticles (NPs) in these areas is infinite, with novel new applications constantly being explored. The possible toxic health effects of these NPs associated with human exposure are unknown. Many fine particles generally considered "nuisance dusts" are likely to acquire unique surface properties when engineered to nanosize and may exhibit toxic biological effects. Consequently, the nuisance dust may be transported to distant sites and could induce adverse health effects. In addition the beneficial uses of NPs in drug delivery, cancer treatment, and gene therapy may cause unintentional human exposure. Because of our lack of knowledge about the health effects associated with NP exposure, we have an ethical duty to take precautionary measures regarding their use. In this review we highlight the possible toxic human health effects that can result from exposure to ultrafine particles (UFPs) generated by anthropogenic activities and their cardiopulmonary outcomes. The comparability of engineered NPs to UFPs suggests that the human health effects are likely to be similar. Therefore, it is prudent to elucidate their toxicologic effect to minimize occupational and environmental exposure. Highlighting the human health outcomes caused by UFPs is not intended to give a lesser importance to either the unprecedented technologic and industrial rewards of the nanotechnology or their beneficial human uses.

Thiolated Chitosan/DNA Nanocomplexes Exhibit Enhanced and Sustained Gene Delivery

PURPOSE

Thiolated chitosan appears to possess enhanced mucoadhesiveness and cell penetration properties, however, its potential in gene-drug delivery remains unknown. Herein, we report on a highly effective gene delivery system utilizing a 33-kDa thiol-modified chitosan derivative.

METHODS

Thiolated chitosan was prepared by the reaction with thioglycolic acid. Nanocomplexes of unmodified chitosan or thiolated chitosan with plasmid DNA encoding green fluorescenct protein (GFP) were characterized for their size, zeta potential, their ability to bind and protect plasmid DNA from degradation. The transfection efficiency of thiolated chitosan and sustained gene expression were evaluated in various cell lines in vitro and in Balb/c mice in vivo.

RESULTS

Thiolated chitosan-DNA nanocomplexes ranged in size from 75 to 120 nm in diameter and from +2.3 to 19.7 mV in zeta potential, depending on the weight ratio of chitosan to DNA. Thiolated chitosan, CSH360, exhibited effective physical stability and protection against DNase I digestion at a weight ratio>or=2.5:1. CSH360/DNA nanocomplexes induced significantly (P<0.01) higher GFP expression in HEK293, MDCK and Hep-2 cell lines than unmodified chitosan. Nanocomplexes of disulphide-crosslinked CSH360/DNA showed a sustained DNA release and continuous expression in cultured cells lasting up to 60 h post transfection. Also, intranasal administration of crosslinked CSH360/DNA nanocomplexes to mice yielded gene expression that lasted for at least 14 days.

CONCLUSIONS

Thiolated chitosans condense pDNA to form nanocomplexes, which exhibit a significantly higher gene transfer potential and sustained gene expression upon crosslinking, indicating their great potential for gene therapy and tissue engineering.

Design of Estradiol Loaded PLGA Nanoparticulate Formulations: A Potential Oral Delivery System for Hormone Therapy

Estradiol (E2), a highly lipophilic molecule with good oral absorption but poor oral bioavailability, was incorporated into poly(lactide-co-glycolide) (PLGA) nanoparticles to improve its oral bioavailability. Nanoparticles were prepared by using polyvinyl alcohol (PVA) or didodecyldimethylammonium bromide (DMAB) as stabilizer, leading to negatively (size 410.9+/-39.4 nm) and positively (size 148.3+/-10.7 nm) charged particles, respectively. Both preparations showed near zero order release in vitro with about 95% drug being released within 45 and 31 days for PVA and DMAB, respectively. In situ intestinal uptake studies in male Sprague-Dawley (SD) rats showed higher uptake of DMAB stabilized nanoparticles. Following oral administration to male SD rats, E2 could be detected in blood for 7 and 2 days from DMAB and PVA stabilized nanoparticles, respectively. Histopathological examination and blood counts indicated the absence of inflammatory response. These data suggest that DMAB stabilized PLGA nanoparticles have great potential as carriers for oral delivery of estradiol.

Preparation and characterization of chitosan and trimethyl-chitosan-modified poly-(epsilon-caprolactone) nanoparticles as DNA carriers

The purpose of this research was to prepare poly-(epsilon-caprolactone) (PCL) particles by an emulsion-diffusion-evaporation method using a blend of poly-(vinyl alcohol) and chitosan derivatives as stabilizers. The chitosan derivatives used were chitosan hydrochloride and trimethyl chitosans (TMC) with varying degrees of quaternization. Particle characteristics-size, zeta potential, surface morphology, cytotoxicity, and transfection efficiency-were investigated. The developed method yields PCL nanoparticles in the size range of 250 to 300 nm with a positive surface charge (2.5 to 6.8 mV). The cytotoxicity was found to be moderate and virtually independent of the stabilizers' concentration with the exception of the highly quaternized TMC (degree of substitution 66%) being significantly more toxic. In immobilization experiments with gel electrophoresis, it could be shown that these cationic nanoparticles (NP) form stable complexes with DNA at a NP:DNA ratio of 3:1. These nanoplexes showed a significantly higher transfection efficiency on COS-1 cells than naked DNA.

New poly(lactic-co-glycolic acid) derivatives: Modular polymers with tailored properties

Poly(lactic-co-glycolic acid) (PLGA) is one of the most widely used polymers in drug delivery, despite several well-characterized shortcomings. Polymer modification is one approach to improve PLGA-based formulation properties, such as drug stability, drug release profiles, mechanism of polymer degradation and the possibility of drug targeting. A brief summary of recent reports on PLGA modifications is provided and a new class of branched polyester derivatives is introduced. In vitro and in vivo applications of the new branched polyesters as protein carriers, gene delivery vehicles, vaccine adjuvants and pulmonary drug delivery vehicles are described.: